Effect of indole and 3-indolylacetonitrile on the heat-resistant CFU of B. subtilis. Glucose (0.5% w/v), indole (1 mM) and 3-indolylacetonitrile (1 mM) were added at the beginning of culture, and cells (an initial turbidity of 0.05 at 600 nm) were grown in spore forming DSM medium at 37°C for 16 h. Glucose (Glu) was dissolved in water, and indole (Ind) and 3-indolylacetonitrile (IAN) were dissolved in DMSO. DMSO (0.1% v/v) was used as a control (None). DMSO (0.1% (v/v)) alone did not affect cell growth and the heat-resistant CFU. Each experiment was repeated three to four times and one standard deviation is shown.